Bushmaster Preadator 556 Jamming

[rtsangio]

Hello,
I'm new to the forum and hope someone can help me. I just purchased a new Bushmaster Preadator and I'm experiencing jamming issues when trying to shoot 556 through it. The lower is stamped 223/556 and will shoot 223 through it all day with no problem. However, when I try and shoot 556 it jams every time on the 2nd-3rd round. I have used PMC 55 grain JHP 223 up to 77 grain JHP 223 with no problem. The 556 I used was 55 grain American Eagle and Winchester FMJ and both jam. Any help/advice would be greatly appreciated.
Thanks, Rob.

[TranterUK]

Welcome to TFF Rob

It would help a lot if you could describe what type of jam your having. Having said that, if its bought new you would be best to return it for the supplier to fix.

[retired grunt]

I have a predator that did the same thing. I pulled the buffer rod and spring cleaned the tube out really well oiled the spring up and reassembled it shoots fine now I think it may be just some crud build up an lack of lubricant. hope this helps

[Crpdeth]

Good quality mags and ammo will also make all the difference in the world.

Crpdeth

[retired grunt]

It does prefer a heavier bullet for sure Wolf ammo still gives me probs

[rtsangio]

I'm having a failure to feed issue. I'm using Magpul mags and the weapon is very clean and well lubed. Like I said it will gobble up 223 ammo all day with no issues so I'm not sure why 556 is such a problem.
Thanks to all for the quick replys.
Rob.

[rtsangio]

I also experienced the same failure to feed issues with the 5 roung mag that came with the weapon?

[USMCSpeedy]

Originally Posted by retired grunt

I have a predator that did the same thing. I pulled the buffer rod and spring cleaned the tube out really well oiled the spring up and reassembled it shoots fine now I think it may be just some crud build up an lack of lubricant. hope this helps

Make sure that the bolt is well lubricated in the bolt carrier as well. Most new ARs of any brand that I've seen come way to dry. A dry bolt can make the spent round not eject correctly and cause feed jams on the next round.

[graehaven]

Pull that bolt back, and squirt oil down right into the chamber, onto the bolt, to assure that it's really well lubricated. You'll have to continue this after shooting through several mags too.

By the way, you did clean it well when it was new before shooting it the first time right?

[rtsangio]

What lube would you suggest? I've been using CLP/Break Free,etc. I just ordered some Slip 2000 and will give that a try. I've heard that automatic transmission fluid work great on bolt carriers too???
Thanks again for the help everyone...
Rob.

[rtsangio]

The weapon was thourouly cleaned before first use and completly stripped and cleaned/lubed afer each outing.
Thanks, Rob.

[USMCSpeedy]

Originally Posted by rtsangio

What lube would you suggest? I've been using CLP/Break Free,etc. I just ordered some Slip 2000 and will give that a try. I've heard that automatic transmission fluid work great on bolt carriers too???
Thanks again for the help everyone...
Rob.

CLP is what they used when I was in the military. I still use it on my weapons. It should be all you need to keep er lubed up right.

[graehaven]

Originally Posted by USMCSpeedy

CLP is what they used when I was in the military. I still use it on my weapons. It should be all you need to keep er lubed up right.

There ya go.

[USMC-03]

+1 on the CLP/Breakfree. Also try some good Colt 20 round or Adventureline 30 round mags, I've had the best luck with them.

[retired grunt]

By jam you mean failure to:

A) extract
B) eject
C) feed next round from magazine
D) chamber next round

Give us more specifics please

[rtsangio]

Failure to feed next round, looks like the bolt is smacking the round as it leaves dents in it. Again, this only happens with 556. 223 works perfect.
Thanks, Rob.

[Helix_FR]

dents on top? Is the bolt missing the back of the next round and passing over leaving a dent were it makes contact a 1/4 inch or so above the rim?

[rtsangio]

Helix,
It's actualy leaving dent up around the shoulder area? I'm going to pay super close attention next time it happens but it looks like sometimes its failure to feed and sometimes failure to eject and then the fresh round gets dented around the shoulder. Any of this making sense??? Only with 556 not 223 I thought they were the same round, no?
Thanks, Rob.

[islenos]

Every gunt knows well the smell, taste and feel of CLP

We drew CLP out of a 55gal barrel and didn't think to much about it. Now CLP is a few bucks for an itty bitty bottle.

[Gene Seward]

The five round mags that they send with the Predator is a piece of junk. I think they should be junked. I agree with the lube and check the gas rings. I had a slight gas leak in mine from the get go, and they fixed it quickly. It may be a small leak that only shows up when shooting the 556.

[Helix_FR]

makes total sense to me. 556 and 223 are similar but 556 runs at higher pressures and the thickness of the brass is greater. This dent that shows up can be a sticking point when the case expands. You may also be getting these dents on the 223 but since its not at as high of pressures its not creating a problem. The extractor still yanks the brass but at the sacrifice of loss of power to complete the cycle so it either stove pipes the removed round or dosent cycle far back enough to chamber a new round. Take a close look at your spent 223.
Mags are a problem too. If the lips of the mag are set to high then next round sits to high and gets the S$&% smacked out of it when the round ejects leaving a nice little dent at the shoulder.
Also check your breech and chamber for burrs. An expanding case can grab and hold and cause problems.
Lube is key but it may only be a band aid for a real problem.

[USMCSpeedy]

Originally Posted by rtsangio

Helix,
It's actualy leaving dent up around the shoulder area? I'm going to pay super close attention next time it happens but it looks like sometimes its failure to feed and sometimes failure to eject and then the fresh round gets dented around the shoulder. Any of this making sense??? Only with 556 not 223 I thought they were the same round, no?
Thanks, Rob.

I've seen this kind of thing before but its usually the other way around and the lower pressure doesn't kick the bolt back far enough with 223. As long as everything is lubed up enough, it sounds like there may be something messed up with the gas system that is more pronounced with the higher pressure 5.56 ammo. Try looking for carbon traces that would indicate gas leaks around where the gas block attaches to the barrel, where the gass tube goes into the block, how the gas tube mates up with bolt carrier key when the bolt is bully closed and locked, and make sure the key is securely bolted to the carrirer.

[rtsangio]

I have been using Magpu P-mags, 30 round.This is a new weapon with less then 1000 rounds through it. Perhaps some more break in and some light hand polishing???
Thanks for the help.
Rob.

[retired grunt]

Going out on a limb here 5.56 normally has thicker brass... I am thinking it's hanging in the mag..slowing the bolt as it comes forward and not carrying into the chamber .... but moving forward till the bolt carrier crushes it behind the shoulder.

I suggest it is a magazine problem after looking at my bushmaster mag i see no easy way to disassemble and clean (the cheap piece o junk)
if you are unable to get different mags to try look closely at the feed lips of the current mag ...a slight bend will matter... lube inside of mag liberally working mag follower up and down and see if it smoothes it up.

[retired grunt]

Also now that I read your using 30 rounders make sure each round is fully seat to the rear of the mag... and the mag is not touching anything as you are firing...Also you can try only loading a handful of rounds and see if it fires the mag spring may be hanging up under full load

I really hope something one of us has suggested helps